Wireless remote telemetry system

ABSTRACT

A wireless remote telemetry system which uses low-cost remote communication devices operating on existing wireless communication systems in order to provide real-time reading and control of remote devices. In an embodiment applicable to utility service, consumption of electrical power among a population of customers is measured by a utility metering system having a wireless communication capability. The metering system comprises a remote metering unit which communicates with a central controller over existing wireless communication systems, such as cellular base stations, using existing communication standards. The remote metering unit transmits various messages over a shared random access channel to a central controller. The central controller transmits messages to the remote metering unit over a paging channel. The remote metering unit may operate in a half-duplex mode only. Furthermore, the remote metering unit may provide a gateway to advanced consumer services at the remote location.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to wireless communications. Moreparticularly, the present invention is directed to a novel and improvedmethod and apparatus for the wireless metering of remote measurementdevices.

II. Description of the Related Art

Many industries utilize remote metering devices to monitor, measure, orrecord critical data. For example, utility companies use utility meterslocated at the customer site to measure utility consumption. Thederegulation of utility companies, such as electric power, water, andnatural gas companies, has prompted these utility companies to seektechnological modernization of equipment and services as a means ofreducing costs in order to compete with other potential utility serviceproviders.

In a conventional utility metering system, each utility customer isbilled according to utility usage over a predetermined period of time,such as one or two months. The utility usage is measured by anelectro-mechanical meter having a visual display such as a set of dials,or an "odometer" type display. A person, typically an employee of theutility company, periodically visits each utility meter in a servicearea to visually read the utility consumption as reported by the meter.

Several inefficiencies exist in conventional utility metering system.For example, the utility company must pay a person to travel to eachmeter to visually read it. This may require sending the meter readerinto a dangerous area. It also takes a long time for a person tophysically visit each meter. Additionally, most electro-mechanicalmeters may be opened and tampered with by a person wishing to reduce hisutility bill. Since the meter is typically read only about once a month,the tampering may not be evident to the utility company. Anotherdrawback to the conventional utility metering system is that local faultdetection, such as the detection of a localized blackout or brown-outcondition, is not possible in real-time because the utility consumptionis not measured in real-time on a local scale.

Furthermore, a typical utility company is forced to maintain a very highpeak-to-average usage ratio. For electrical power companies, thispeak-to-average usage ratio may be on the order of 12:1, requiring thepower company to maintain about twelve times as much equipment as wouldbe required for a constant, average load. The conventional meteringsystem does not provide any real-time way to minimize peak loadingconditions. Clearly this is a very significant cost in providing utilityservices. Conventional attempts to control peak-to-average usage ratioinclude billing at a higher rate for all usage above a predeterminedquantity. However, it is not currently possible in the conventionalsystem to perform this billing increase in real-time because it is notuntil the meter is read that the utility company can determine theamount of usage. Likewise, there the prior art metering system does notmonitor real-time loading conditions on a local scale in order toprovide for more accurate usage forecasting and equipment installationplanning.

In a competitive market, the utility company could also greatly benefitfrom the integration of other services with utility services. In arelated area, "smart" homes are being designed which provide a highlevel of integration of consumer services such as telephone, cabletelevision, computer network services, home shopping, paging, and thelike. Additionally, these "smart" homes may utilize Consumer ElectronicBus (CEBus EIA/ANSI-600) technology to enable the owner to remotelycontrol various household appliances and devices using power-linecarriers over the existing power lines in the home. The purpose of CEBustechnology is to allow consumer appliances and devices to work togetheras an integrated home or industry system. CEBus-compliant devices canshare information with other CEBuscompliant devices. Among othercommunication media, the CEBus standard supports communication overpre-existing power line and twisted pair cabling. Power linetransceivers typically use a 100 to 400 KHz spread-spectrum carriertechnology, while twisted pair transceivers use a simple 10 KHz, 250 mVcarrier. However, with the traditional metering system, the utilitycompany does not have the infrastructure to take advantage of thisintegration.

The problems facing the utility companies in this area are similar toproblems facing companies in other industries that have a need toremotely monitor, measure or control a metering device or point-of-sale.For example, mail delivery companies, such as the U.S. Postal Service orthe like, generally maintain a large number of mail drop-off points.Each day, these drop off points must be checked to see if any mail hasbeen deposited for delivery. Often times, especially in rural areas,there is no mail at the remote mailbox when the postal employee arrivesto check it. The result is inefficient deployment of resources.Likewise, vending machine companies must send employees out to serviceremote vending machines according to a predetermined schedule, withoutknowing what the actual demand has been at the machine until theemployee arrives. Clearly, there are many industries that face similarinefficiencies that arise from scheduled servicing of remote stationsrather than event-driven demand-side management of these remotestations.

Several prior art solutions have been proposed for overcoming theseefficiencies. Many of these prior art solutions involve the design andinstallation of new, dedicated communication systems to service theremote telemetry devices. Such prior art solutions make initialdeployment of the system cost prohibitive. Other prior art solutionsavoid high initial costs by using existing cellular radiotelephonesystems to provide the communication link with the remote telemetrydevice. However, a significant drawback to these systems is their lackof capacity, preventing them from servicing large urban areas due to apotential overload of the cellular system overhead channels which wouldprevent normal cellular phone customers from receiving reliable service.Still other prior art solutions use unlicensed radio frequency (RF)bands to transmit their remote telemetry data, resulting in asignificant loss of reliability due to interference from otherunlicensed users in the same RF band.

What is needed is a remote telemetry system which avoids thedisadvantages of the prior art telemetry systems by providing real-timetelemetry data information in a low-cost and efficient manner, whilefurther providing a "gateway" for providing advanced consumer servicesat the remote location.

SUMMARY OF THE INVENTION

The present invention is a novel and improved wireless and remotetelemetry system which uses low-cost remote communication devicesoperating on existing wireless communication systems in order to providereal-time reading and control of remote telemetry devices. For example,in an embodiment applicable to utility service, consumption ofelectrical power among a population of customers such as residentialhomes and commercial buildings, is measured by a utility metering systemhaving a wireless communication capability. The metering systemcomprises a remote metering unit which communicates with a centralcontroller over existing wireless communication systems, such ascellular base stations, using existing communication standards.

The remote metering unit transmits various messages to the centralcontroller according to a predetermined schedule which may be remotelyset and adjusted by the central controller. The messages that the remotemetering unit transmits to the central controller include utilityconsumption readings and fault status indications. These messages aretransmitted over a shared random access channel. The central controllertransmits messages to the remote metering unit over a paging channel,providing control functions such as setting the reporting interval ofthe remote metering units, and acknowledging receipt of messages fromthe remote metering unit. The remote metering unit may operate in ahalf-duplex mode only, thus eliminating the need for more costlycomponents such as a duplexer which are required for full-duplexoperation.

The system also may provide various advanced services such as deliveringreal-time rate information to the remote metering unit to shift demandduring peak hours, remote notification of the building owner upon afault condition in the utility service or metering system, and real-timecontrol functions such as load balancing in order to minimize peakusage. The system also provides various techniques to manage thereporting load on the system during peak reporting times, such as duringa widespread blackout. Furthermore, the remote metering unit may providea gateway to advanced consumer services at the remote location.

By providing wireless and automatic metering services, the utilitycompany may decrease costs by avoiding labor-intensive sight-reading ofmeters. Also, the utility company may use real-time data to monitor andadjust the load in response to surges and dips in demand. Since thesevariations are detected in real-time, the supply can be adjusted or thedemand shifted by pricing increases during peak usage times or directcontrol of remote appliances, thereby reducing the peak-to-averageratio. Information collected for individual customers may be processedin real-time to generate short and long-term usage forecasts.Simultaneous readings of multiple remote metering units throughout thedistribution system provides real-time location of losses, servicethefts, leaks and faulty or improperly measuring meters. Accuratefeedback of usage behavior may be provided to customers in billingstatements in order to more accurately target and control wastefulpractices and satisfy conservation goals.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of the present invention willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout and wherein:

FIG. 1 is an overview of the remote telemetry system of the presentinvention, illustrated in block-diagram format; and

FIG. 2 is a block-diagram of an exemplary remote metering unit of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates, in block diagram format, an overview of the remotetelemetry system 100 of the present invention. It should be noted thatalthough the present invention will be described with respect toelectrical power service, its teachings are equally applicable to otherutility companies, such as water and natural gas service providers, aswell as other industries as previously discussed which have a need toremotely monitor, control, or service a remote station.

A plurality of remote metering units 102a-102n are respectively locatedat strategic points throughout the utility distribution network. Forexample, the remote metering units 102a-102n would be located atresidential homes and commercial buildings where the end-use of theutility service occurs, as well as key distribution points such assubstations and the like where larger-scale monitoring is desired. Theremote metering units 102a-102n may be comprised of, for example, abasic transceiver coupled to a pre-existing conventionalelectro-mechanical utility meter by an interface device which is adaptedto the type of meter (i.e. dial or odometer type). An advantage of thisconstruction is that a small, low-cost, and easy to manufacture devicemay be readily adapted to be installed on pre-existing meters withoutcostly system upgrading. Such a remote metering unit is described belowwith reference to FIG. 2.

In alternate embodiments, the remote metering units 102a-102n areintegral units which combine the utility measurement and communicationcircuits into a single device. An advantage of the integral constructiondesign is reduced size and weight of the entire unit, making it morecost-effective and attractive for installation in newly constructedbuildings, particularly if it is CEBus-compliant.

In the preferred embodiment, the remote metering units 102a-102n eachperform basic metering functions including reporting of utility serviceconsumption, meter tampering detection and reporting, utility outagereporting, and detection and reporting of "surges" and "dips" in servicelevels. The remote metering units 102a-102n each transmit theirreporting messages to central controller 116 by using a conventionalwireless communication system comprising at least one base station 108and a mobile telephone switching office (MTSO) 110, which interfaceswith the public switched telephone network (PSTN) 112. Centralcontroller 116 may comprise, for example, a network-capable computer andassociated memory databases and interface circuitry running applicationspecific software for performing the control functions described herein.In various embodiments to be described below, various intermediate stepsor "hops" may be interposed between the remote metering units 102a-102nand the central controller 116 including a wireless repeater 118, a homebase unit 122, or a mobile base unit 130. Each of these variousembodiments may co-exist in the same large-scale system.

In the preferred embodiment, base station 108 and MTSO 110 belong to aCode-Division Multiple Access (CDMA) spread spectrum communicationsystem. An example of such a system is given in U.S. Pat. No. 4,901,307,issued Feb. 13, 1990, entitled "SPREAD SPECTRUM MULTIPLE ACCESSCOMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS," assignedto the assignee of the present invention, and incorporated herein byreference. Additionally, the wireless communication system may bedesigned in accordance with Telecommunications Industry Association(TIA)/Electronic Industries Association (EIA) Interim Standard 95(IS-95) entitled "Mobile Station-Base Station Compatibility Standard forDual-Mode Wideband Spread Spectrum Cellular System." Alternatively, thewireless communication system may be designed in accordance with ANSIJ-STD-008, entitled "Personal Station Base Station CompatibilityRequirements for 1.8 to 2.0 GHz Code Division Multiple Access (CDMA)Personal Communications Systems." However, it should be noted that theteachings of the present invention are applicable to other wirelesscommunication systems whether cellular or non-cellular, and regardlessof the modulation scheme employed. For example, the present invention isequally applicable to Time-Division Multiple Access (TDMA) based systemssuch as the U.S. TDMA standard IS-54, or the pan-European standardGlobal System for Mobile Communications (GSM). Additionally, theteachings of the present invention are applicable to analog frequencymodulation communication systems, such as the Advanced Mobile PhoneSystem (AMPS).

In a first embodiment based on one of the previously mentioned CDMAstandards, the remote metering units 102a-102n transmit their respectivereporting messages to a respective remote communication unit located atthe customer site. The remote communication unit may be for example, awireless subscriber terminal or a specially designed mini-base station.For example, remote metering unit 102n of FIG. 1 is shown communicatingwith home base unit (HBU) 122 over communication link 124. In this firstembodiment, link 124 is an electrical power line capable of employingpower-line carrier (PLC) modulation, and both remote monitoring unit102n and HBU 122 employ PLC transceivers. Alternately, link 124 may bean RF link over a licensed or unlicensed RF band, in which case bothremote metering unit 102n and HBU 122 would employ RF transceivers. Anadvantage to using an RF interface for link 124 is that the transmittingpower, and thus the cost, of remote metering unit 102n is small due tothe relatively short distance between remote metering unit 102n and HBU122. However, a drawback to the unlicensed approach is that theunlicensed band is susceptible to unregulated interference from other RFemitters, such as microwave ovens.

In this first embodiment, HBU 122 preferably collects and transmits thereporting messages generated by remote metering unit 102n to basestation 108 over access channel 106. The access channel 106 is a randomaccess CDMA channel which nominally provides for call originations,responses to pages, orders, and registrations for conventionalsubscriber stations 140 such as cellular radiotelephones. Conversely,control messages, orders, and responses to reporting messages aretransmitted from base station 108 over paging channel 104. Pagingchannel 104 is a CDMA channel which nominally conveys overhead, paging,order and channel assignment messages to conventional subscriberstations 140 such as cellular radiotelephones. In this first embodiment,HBU 122 receives the control messages, orders, and responses toreporting messages from base station 108 over paging channel 104, andrelays them to remote metering unit 102n for action as required.However, it should be noted that in alternate embodiments, HBU 122 mayutilize a pre-installed land-line communication link 126 directly to thePSTN in order to communicate with central controller 116. This alternateembodiment would have the advantage of reduced cost of communication ifa pre-existing land-line communication link 126 already existed at theremote station.

In this first embodiment, HBU 122 may include an integrated RS-232serial port, or CEBus transceiver, or the like for interface to a userterminal 132 such as a personal computer or a fax machine. Thus, HBU 122would serve as an interface for the customer to receive and displayinformation sent over paging channel 104 to HBU 122. For example,real-time billing data, account status inquiries and various othervalue-added services such as advertising services could be displayed bythe customer at user terminal 132. During peak utility usage hours,real-time pricing information could be communicated from centralcontroller 116 to the customer at user terminal 122, prompting thecustomer to reduce his power consumption by turning off variousnon-critical electrical equipment. Furthermore, user terminal 132 mayprovide for interactive consumer services such as home-shopping, travelreservations, concert ticket sales, and the like.

For example, a customer desiring to purchase airline ticket reservationsmay enter the appropriate information at user terminal 132 which isrunning application specific software for remote airline purchases. Theuser terminal 132 generates a purchase message which is encoded,modulated and transmitted by HBU 122 over access channel 106 to basestation 108. The purchase message is routed by MTSO 110 and PSTN 112 tocentral controller 116 where appropriate action is taken (i.e.reservation of the tickets, debiting of the customer's checking account,etc.). A confirmation message is then generated by central controller116 which is routed by PSTN 112 and MTSO 110 to base station 108. Basestation 108 then encodes, modulates, and transmits the confirmationmessage over paging channel 104. The confirmation message is received byHBU 122, and passed to user terminal 132 for display to the customer.

Additionally, HBU 122 may have an application interface that allowsremote scheduling of automatic meter readings, automatic billinginformation transfer, and the like, based on control messages sent fromcentral controller 116. In alternate embodiments, remote metering unit102n may itself have a direct interface with user terminal 132, whetherit be RS-232, or PLC or another interface technology as is known in theart.

HBU 122 may also serve as a "gateway" for other services relating tohome-integration and utility load management. For example, considerCEBus-compliant appliance 136 connected to HBU 122 via PLC interface138. Appliance 136 may be a lighting fixture, heating/air conditioningunit, security system, or home entertainment system for example. Duringpeak hours, central controller 116 could send control messages toappliance 136, or a group of appliances on a common bus, to turn off,thus reducing real-time power loading. Also, a customer could remotelyactivate and deactivate appliance 136 by sending control messages fromconventional subscriber station 140 to appliance 136 via base station108 and HBU 122.

In a second embodiment of the present invention, a localized group ofremote metering units, for example 102a-102c, may comprise a low-powerCDMA transceiver such as that described with reference to the firstembodiment. However, instead of the HBU 122 providing the intermediate"hop" to base station 108, a CDMA repeater 118 would relay RF signalsover access channel 106 from remote metering units 102a-102c to basestation 108, and also relay RF signals over paging channel 104 from basestation 108 to remote metering units 102a-102c. CDMA repeater 118 wouldcomprise, for example, a high-power amplifier and associatedtransponding circuitry as is known in the art. CDMA repeater 118 couldbe located, for example, at the top of a utility pole, or on a rooftopwhere it had sufficient line-of-sight communication with both remotemetering units 102a-102n and base station 108.

An advantage of using CDMA repeater 118 to relay messages back and forthbetween remote metering units 102a-102c and base station 108 is that theRF power output of remote metering units 102a-102c, and consequentlytheir cost, would be reduced significantly over embodiments where remotemetering units 102a-102c must each transmit enough power to contact basestation 108 directly over access channel 106. Although remote meteringunits 102a-102c would be on the order of 500 feet to 1,000 feet fromCDMA repeater 118, the repeater 118 itself could be on the order of sixor seven miles from the nearest base station 108. Additionally, CDMArepeater 118 is much less complex and less expensive to manufacture,install and maintaing than base station 108. Thus, the effectivecoverage area of base station 108 may be extended by CDMA repeater 118without the need for additional base stations.

To provide the "gateway" of demand-side services referred to above inthe discussion of the first embodiment, the PLC interface may be locatedinside remote metering units 102a-102c themselves as will be discussedfurther with reference to FIG. 2. As previously noted, this secondembodiment may be used in combination with any of the other embodimentsdiscussed herein. Additionally, it should be noted that CDMA repeater118 could utilize a wireline backhaul interface to base station 108 suchas fiber optic lines or the like, depending on the nature of theinstallation site, and availability of wireline resources near theinstallation site. Such a fiber-optic outfitted repeater 118 wouldinclude the same RF link to the remote metering units 102a-102n as wasdiscussed above, but would have a fiber optic link backhaul to the basestation 108.

In a third embodiment of the present invention, remote metering units102a-102n communicate directly with base station 108 over access channel106, and receive messages from base station 108 over paging channel 104.In this third embodiment, remote metering units 102a-102n would requirea higher-power transceiver than that used for the first and secondembodiments. However, initial installation and retrofitting of existingmeters would be easier because HBU 122 and CDMA repeater 118 would notbe needed. As in the second embodiment, the PLC gateway for value-addedservices would be located in the respective remote metering units102a-102n.

In a fourth embodiment of the present invention, a mobile base unit(MBU) 130 may be located in a vehicle 128 and driven to withincommunication range of remote metering units 102a-102n. This fourthembodiment may be used to augment coverage in rural areas that do notyet have wireless communication services installed. This fourthembodiment utilizes the same low-power CDMA RF transceiver in remotemetering units 102a-102n as was described above in reference to thefirst and second embodiments. Additionally, MBU 130 is functionally verysimilar to HBU 122 as described above in that it collects and transmitsmessages from remote metering units 102a-102n, except that it isconfigured for mobile operations, and thus is not in continuouscommunication with remote metering units 102a-102n. MBU 130 may alsocomprise a separate computer (not shown) for data storage andpost-processing instead of immediate transmission to base station 108.In this fourth embodiment, since MBU 130 is not in continuouscommunication with remote metering units 102a-102n, MBU 130 interrogateseach remote metering unit 102a-102n as it drives by, receiving repliesfor storage and later post-processing.

In each of the above described embodiments, multiple remote meteringunits 102a-102n may simultaneously attempt to send a message on accesschannel 106, either alone or through their respective intermediate"hops" (i.e. HBU 122, or repeater 118), at the same time that otherconventional subscriber units 140 are also attempting to communicatewith base station 108 over access channel 106. Thus, techniques foravoiding "collisions" between competing remote metering units 102a-102nare provided. For example, a transmitting remote metering unit 102a-102nrandomly chooses a pseudo-noise (PN) time alignment from the set ofavailable PN time alignments. Thus, unless two or more remote meteringunits 102a-102n or other remote subscriber stations choose the same PNtime alignment, the base station 108 will be able to receive theirsimultaneous transmissions. The base station 108 also controls the rateof access channel 106 transmissions to prevent too many simultaneoustransmissions by multiple subscriber stations. Too many simultaneoustransmissions would exhaust the available capacity of the access channel106 and ultimately exhaust the available base station 108 processingresources. Normal control of access channel 106 transmissions isaccomplished through parameters contained in an Access ParametersMessage, broadcast from base station 108 on paging channel 104.

A further technique for preventing system overload due to too manysimultaneous users is active scheduling of the remote metering units102a-102n reporting times by central controller 116. Central controller116 generates scheduling messages for delivery to each remote meteringunit 102a-102n. In the preferred embodiment, these scheduling messagesare routed from PSTN 112 through MTSO 110 to base station 108 where theyare transmitted over paging channel 104. Examples of scheduling messageswould be a broadcast instruction for each remote metering unit 102a-102nto transmit their respective reporting messages at a randomly selectedtime, once per hour. Another example of a scheduling message would be aspecific interrogation of a specific remote metering unit 102a, forexample, to set a baseline for the commencement of utility services, orthe closing of an account. A further type of collision avoidance schememay be employed when a catastrophe such as a blackout condition occurs,and thus many thousand remote metering units 102a-102n eachsimultaneously want to transmit a fault status indication message tocentral controller 116. In such a catastrophe, central controller 116may send out a broadcast message via base station 108 directing onlycertain strategically located remote metering units 102a-102n to report,or to distribute their reporting messages over time by hashing.

In alternate embodiments, a paging channel 104 and an access channel 106may be constructed that are optimized for short message transmissions bya large population of remote metering units 102a-102n. Such a system isdescribed in co-pending U.S. pat. application Ser. No. 08/412,648, filedMay 17, 1995, entitled "RANDOM ACCESS COMMUNICATIONS DATA CHANNEL FORDATA SERVICES," assigned to the assignee of the present invention andincorporated herein by reference. In the just mentioned patent, each ofthe remote subscriber stations, here the remote metering units102a-102n, uses a unique PN spreading code and makes packet servicerequests on the random access channel 106. In response to the packetservice request, the base station 108 assigns a free searcher receiver(not shown) to the requesting station and acknowledges the request onthe paging channel 104. The remote subscriber station then sends thedata packet on the random access channel 106 where it is discriminatedby the searcher receiver, and demodulated. If the bandwidth demand ofthe remote subscriber station exceeds a certain threshold (i.e. thelength of the data packet exceeds a certain threshold), the base station108 would send a control message over the paging channel 104 to assignthe remote subscriber station to a dedicated traffic channel (not shown)for transmission of the data packet.

Additionally, in this alternate embodiment, closed-loop power controlcommands are sent to the remote subscriber units over the paging channel104 to ensure that all transmissions arrive at the base station 108 withthe same average power. For example, the base station 108 may performclosed-loop power control in accordance with the techniques described inU.S. Pat. No. 5,257,283, issued Oct. 26, 1993, entitled "SPREAD SPECTRUMTRANSMITTER POWER CONTROL METHOD AND SYSTEM," assigned to the assigneeof the present invention and incorporated herein by reference. Thisalternate embodiment is particularly suited for sharing communicationchannel resources among a large number of "bursty" packet data users,each having a variable and unpredictable demand for base station 108resources. Clearly there are many different possible constructions forpaging channel 104 and access channel 106.

In the preferred embodiment, remote metering units 102a-102n operate inhalf-duplex mode. That is to say that the remote metering units102a-102n do not receive messages over paging channel 104 from the basestation 108 at the same time that they are transmitting messages to basestation 108 over access channel 106. Furthermore, in the preferredembodiment, the paging channel 104 operates in "slotted" mode. In thismode, messages addressed to a particular remote subscriber station, herethe remote metering units 102a-102n, are sent only in pre-defined timeslots. Through the registration process, a remote subscriber stationindicates to base station 108 in which slots it will be "listening" topaging channel 104 for messages addressed to it. Thus, in the preferredembodiment, remote metering units 102a-102n may operate in half-duplexmode without missing any incoming messages on paging channel 104 bytransmitting reporting messages on access channel 106 only during timesother than their respective assigned slots on the paging channel 104. Byutilizing half-duplex mode operation, the remote metering units102a-102n may be manufactured much more inexpensively because they avoidthe need for a duplexer and allow possible sharing of a single frequencysynthesizer for both transmit and receive paths.

Referring now to FIG. 2, an exemplary remote metering unit 102 isillustrated. In an embodiment applicable to electrical utility meterreading, measurement device 202 may be an electro-mechanical powerconsumption monitor and display of the rotating disk or odometer typesas are known in the art. Reading interface 204 may then be an optical orelectro-mechanical interface adapted to the type of measurement device202 employed. For example, if measurement device 202 is anelectro-mechanical rotating disk, then the number of revolutions of thedisk is indicative of the power consumption. In such a case, readinginterface 204 may comprise a light source and photocell that reads asingle light pulse for every revolution of the disk. Reading interface204 transforms the light pulses to analog electrical pulses andtransmits them to analog multiplexer (AMUX) 208, where they are passedto analog-to-digital converter (A/D) 210. A/D converts the analogelectrical pulses to a digital signal representative of the number ofrevolutions counted by reading interface 204, and passes the resultingdigital signal to microprocessor 214. In response to the digital signal,microprocessor 214 calculates and stores the total consumption inkilowatt hours. In the preferred embodiment, the storage interval may beselectable from about one-half hour to about one month.

Periodically, according to a reporting schedule that may either beprogrammed locally or downloaded over paging channel 104 from centralcontroller 116 (see FIG. 1), microprocessor 214 generates a utilityconsumption message for transmission on access channel 106. Theconsumption message is formatted by microprocessor 214 and thenupconverted, modulated, amplified, and transmitted by transmitter 216over antenna 222. Note that in the preferred embodiment, microprocessor214 configures switch 220 for transmission only during times other thanthe assigned paging slot on paging channel 104, thereby enabling remotemetering unit 102 to operate half-duplex without missing incomingmessages from central controller 116. Alternately, switch 220 may bereplaced by a conventional duplexer as is known in the art ifhalf-duplex operation is not desired.

Control or feedback messages intended for remote metering unit 102 aretransmitted by central controller 116 as previously discussed. Thesemessages are captured by antenna 222, downconverted and demodulated byreceiver 218 and passed to microprocessor 214 for appropriate action.Note that microprocessor 214 configures switch 220 for reception unlessan outgoing transmission is required. The control messages sent bycentral controller 116 may include scheduling messages andacknowledgment of receipt of the various reporting messages transmittedby remote metering unit 102.

Additionally, in the exemplary embodiment of FIG. 2, voltage step-downtransformers 206a and 206b are respectively coupled to the phase A andphase B electrical power lines at the customer site. In a typicalelectrical power installation in a residential home in the UnitedStates, the voltage level of both phase A and phase B is 120 volts.Step-down transformers 206a and 206b each output an analog voltage levelsignal that is proportional to the voltage sensed on phase A and phaseB, respectively. The analog voltage level signals are passed to A/D 210by AMUX 208, where they are subsequently converted to digital voltagelevel signals. The digital voltage level signals are then passed tomicroprocessor 214 through serial interface 212, where they arerespectively compared with a maximum and a minimum voltage levelthreshold. In the preferred embodiment, the maximum and minimum voltagelevel thresholds are programmable, and may be enabled or disabled viacontrol messages from central controller 116, as required.

If the digital voltage level signal representing the voltage sensed onphase A, and the digital voltage level signal representing the voltagesensed on phase B are both between the maximum and minimum voltage levelthresholds, then the voltage level regulation of phase A and phase B issatisfactory, and no action is taken. However, if either the digitalvoltage level signal representing the voltage sensed on phase A, or thedigital voltage level signal representing the voltage sensed on phase Bis not between the maximum and minimum voltage level thresholds, thenthe voltage level regulation of phase A and phase B is unsatisfactory,and microprocessor 214 generates a fault condition message fortransmission to central controller 116 (see FIG. 1). Such a faultcondition would occur if there were excessive "surges" or "dips" in thevoltage level sensed on phase A or phase B, including if there were alocal blackout or brownout. The fault condition message may contain anencoded representation of the actual voltage sensed on phase A and phaseB.

Microprocessor 214 may generate the fault condition message forimmediate transmission to central controller 116, or store the digitalvoltage level signal for delayed reporting. The delayed reportingfeature may be used in conjunction with the broadcast message previouslydiscussed in the case of a blackout, where thousands of remote meteringunits 102 would be experiencing the same fault condition, and thusaccess channel 106 would have to be carefully managed to avoid exceedingsystem capacity. Furthermore, central controller 116 may periodicallyinterrogate remote metering unit 102 and direct it to report not onlythe present consumption reading, but also the present voltage levelssensed on both phase A and phase B.

Additionally, in the exemplary embodiment of FIG. 2, a tampering sensor238 generates an analog tampering signal upon any attempted alterationor disconnection of remote metering unit 102. Tampering sensor 238 maybe, for example, a mercury switch, or a proximity switch as is known inthe art. This is desired in a utility metering application sincetampering with the meter in order to "steal" utility service is verycommon. Since no person will be regularly visiting the remote meteringunit 102 for visual inspection, the tampering sensor 238 is a securityfeature that enables remote detection of theft. The analog tamperingsignal is passed to A/D 210 through AMUX 208, where it is subsequentlyconverted to a digital tampering signal. The digital tampering signal ispassed to microprocessor 214 through serial interface 212.Microprocessor 214 may generate an fault condition message for immediatetransmission to central controller 116, or it may provide for memorystorage of the digital tampering signal for delayed reporting. In caseremote metering unit 102 is disconnected, the digital tampering signalis stored in memory for later retrieval.

In the exemplary embodiment shown in FIG. 2, CEBus interface 224, powerline transceiver 226, and twisted pair transceiver 234 are shown asbeing an integral part of remote metering unit 102. However, it shouldbe noted that these "gateway" devices may be located at HBU 122 (seeFIG. 1). Additionally, it should be noted that whether twisted pairtransceiver 234 or power line transceiver 226 are located integrally toremote metering unit 102, or whether they would be present at all, maydepend on the nature and configuration of the installation site. Also,it should be noted that although the CEBus interface 224, power linetransceiver 226 and twisted pair transceiver 234 are shown as physicallyseparate blocks in FIG. 2, they may be integrated into a singleVery-Large Scale Integration (VLSI) Application Specific IntegratedCircuit (ASIC), and even combined into microprocessor 214. VLSI ASICtechniques are well known in the art.

In the preferred embodiment, CEBus interface 224 comprises a flash EPROMprogrammed with the specific application code required to run thevarious advanced services described herein. Additionally, CEBusinterface 224 comprises non-volatile memory for storing CEBus systemconfiguration parameters. Finally, CEBus interface 224 comprises therequired circuitry for interfacing with microprocessor 214 and bothpower line transceiver 226 and twisted pair transceiver 234. Forexample, CEBus interface 224 may further comprise an embedded UART (notshown) for transmitting at higher data rates over twisted pairtransceiver 234. CEBus controllers and interfaces are well known in theart. Power line transceiver 226 and twisted pair transceiver 234 eachcomprise the necessary circuitry to perform carrier modulation. This mayinclude amplifiers, receivers, transformers, and various passiveelements. Power line and twisted pair transceivers are also well knownin the art.

In operation, control or informational messages originating in centralcontroller 116, or alternately conventional subscriber station 140, arereceived by receiver 218, and passed to microprocessor 214 where theyare subsequently routed to CEBus interface 224. In response to thecontrol or informational messages, CEBus interface 224 generates PLCencoded messages for transmission by either twisted pair transceiver 234or power line transceiver 226, or both. The PLC encoded messages aretransmitted on power lines 228 and 230 respectively, or on twisted pairline 232. CEBus-compliant appliance 136 receives the PLC encodedmessages, decodes them, and takes appropriate action.

For example, referring back to FIG. 1, appliance 136 may be a thermostatwhich controls a heating/air-conditioning unit. Central controller 116may sense that the overall peak load on the local grid to which remotemetering unit 102n belongs is exceeding a predetermined threshold. Inresponse, central controller 116 may generate a control messageinstructing various equipment in the local grid to shed a portion oftheir load. The control message may be routed by PSTN 112 and MTSO 110to base station 108. In response, base station 108 may transmit asignaling message intended for remote metering unit 102n over pagingchannel 104. Referring now to FIG. 2, the signaling message may bereceived by receiver 218, and passed by microprocessor 214 to CEBusinterface 224. In response, CEBus interface 224 may then generate a PLCencoded message for transmission on power lines 228 and 230 to appliance136 (the thermostat). In response to the PLC encoded message, thethermostat would adjust its settings to reduce the power load, forexample by turning off the heating/air-conditioning unit. A similarprocess would be followed for any CEBus-compliant appliance 136 at thecustomer site. In this manner, the utility company may provide foractive load management functions, thereby reducing their peak-to-averageratio. Furthermore, the same process may be used to easily accomplishrestoration of power service (i.e. connecting and disconnecting ofelectricity service) as long as power relay switches (not shown) areinstalled at the customer site and are CEBus-compliant.

Additionally, any CEBus-compliant appliance 136 may share informationabout its own operational state. For example, suppose appliance 136 is ahome security system having a controller. Upon a breach of the homesecurity system, the home security system controller generates an alarmmessage, and PLC encodes it over power lines 228 and 230. Power linetransceiver 226 receives the alarm message, and passes it to CEBusinterface 224, which decodes it and passes it to microprocessor 214. Inresponse, microprocessor 214 generates an appropriate alarm statusmessage which is subsequently transmitted by transmitter 216, overaccess channel 106 (see FIG. 1) to base station 108. The alarm statusmessage may then be routed to central controller 116 by MTSO 110 andPSTN 112 where appropriate security personnel may be notified torespond.

The format of the various messages sent over paging channel 104 andaccess channel 106 will now be discussed with reference to a system 100which is compliant with J-STD-008. Again, it should be noted that theteachings of the present invention are equally applicable to otherstandards. In the preferred embodiment of the present invention, thevarious reporting messages transmitted by remote metering units102a-102n over access channel 106 use the format of the Data BurstMessage of ANSI J-STD-008 paragraph 2.7.1.3.2.3. The Data Burst Messageis a variable length message suitable for the formatting of shortmessages. The format of a Data Burst Message is given below in referenceto TABLE I:

                  TABLE I                                                         ______________________________________                                        Access Channel Data Burst Message Format                                      Field               Length (Bits)                                             ______________________________________                                        MSG.sub.-- TYPE     8                                                         ACK.sub.-- SEQ      3                                                         MSG.sub.-- SEQ      3                                                         ACK.sub.-- REQ      1                                                         VALID.sub.-- ACK    1                                                         ACK.sub.-- TYPE     3                                                         MSID.sub.-- TYPE    3                                                         MSID.sub.-- LEN     4                                                         MSID                8 X MSID.sub.-- LEN                                       AUTH.sub.-- MODE    2                                                         AUTHR               0 OR 18                                                   RANDC               0 OR 8                                                    COUNT               0 OR 6                                                    MSG.sub.-- NUMBER   8                                                         BURST.sub.-- TYPE   6                                                         NUM.sub.-- MSGS     8                                                         NUM.sub.-- FIELDS   8                                                         CHARi               8                                                         ______________________________________                                    

where:

MSG₋₋ TYPE is the message type. For the Data Burst Message, the messagetype is `00000011`.

ACK₋₋ SEQ is the acknowledgment sequence number. The remote meteringunit 102 shall set this field to the value of the MSG₋₋ SEQ field fromthe most recently received Paging Channel message requiringacknowledgment. If no such message has been received, the remotemetering unit shall set this field to `111`.

ACK₋₋ REQ is the acknowledgment required indicator. This field indicateswhether this message requires an acknowledgment. The remote meteringunit 102 shall set the ACK₋₋ REQ field of all messages on access channel106 to `1`.

VALID₋₋ ACK is the valid acknowledgment indicator. To acknowledge apaging channel 104 message, the remote metering unit 102 shall set thisfield to `1`. Otherwise the remote metering unit shall set this field to`0`.

ACK₋₋ TYPE is the acknowledgment address type. The remote metering unit102 shall set this field to the value of the ADDR₋₋ TYPE field, ifpresent, from the most recently received paging channel 104 messagerequiring acknowledgment. Otherwise, the remote metering unit 102 shallset this field to `000`.

MSID₋₋ TYPE is the personal station identifier field type. The remotemetering unit 102 shall set this field in accordance with the type ofidentifier being used (i.e. ESN, IMSI, TMSI, etc.)

MSID₋₋ LEN is the personal station identifier field length. The remotemetering unit 102 shall set this field to the number of octets includedin the MSID field.

MSID is the personal station identifier. The remote metering unit 102shall set this field to the personal station identifier, using theidentifier type specified in the MSID₋₋ TYPE field.

AUTH₋₋ MODE is the authentication mode. If authentication information isnot available, or if base station 108 has indicated that authenticationis not required, the remote metering unit 102 shall set this field to`00`. If authentication is required by the base station andauthentication information is available, the remote metering unit 102shall set this field to `01`.

AUTHR is the authentication data. If the AUTH₋₋ MODE field is set to`00` this field shall be omitted.

RANDC is the random challenge value. If the AUTH₋₋ MODE field is set to`00` this field shall be omitted.

COUNT is the call history parameter. If the AUTH₋₋ MODE field is set to`00` this field shall be omitted.

MSG₋₋ NUMBER is the message number within the data burst stream. Theremote metering unit 102 shall set this field to the number of thismessage within the data burst stream.

BURST₋₋ TYPE is the data burst type, and is set according to the valueshown in TSB-58, entitled "Administration of Parameter Value Assignmentsfor TIA/EIA Wideband Spread Spectrum Standards" for the type of thisdata burst.

NUM₋₋ MSGS is the number of messages in this data burst stream.

NUM₋₋ FIELDS is the number of characters in this message.

CHARi is a character. The remote metering unit 102 shall include NUM₋₋FIELDS occurrences of this field. The remote metering unit 102 shall setthese fields to the corresponding octet of the data burst stream.

Alternate embodiments use different message formats to carry thereporting messages generated by remote metering unit 102. For example,the Origination Message of ANSI J-STD-008 may be used with the messagedata contained in the CHARi (dialed digit or character) field.

In the preferred embodiment, for control messages sent by base station108 over paging channel 104, the Data Burst Message format of ANSIJ-STD-008 paragraph 3.7.2.3.2.9 is used. The Data Burst Message is avariable length message format suitable for short messages. The formatof the Data Burst Message is described below with reference to TABLE II:

                  TABLE II                                                        ______________________________________                                        Paging Channel Data Burst Message Format                                      Field               Length (Bits)                                             ______________________________________                                        MSG.sub.-- TYPE     8                                                         ACK.sub.-- SEQ      3                                                         MSG.sub.-- SEQ      3                                                         ACK.sub.-- REQ      1                                                         VALID.sub.-- ACK    1                                                         ADDR.sub.-- TYPE    3                                                         ADDR.sub.-- LEN     4                                                         ADDRESS             8 x ADDR.sub.-- LEN                                       MSG.sub.-- NUMBER   8                                                         BURST.sub.-- TYPE   6                                                         NUM.sub.-- MSGS     8                                                         NUM.sub.-- FIELDS   8                                                         CHARi               8                                                         ______________________________________                                    

where:

MSG₋₋ TYPE is the message type. For the Paging Channel Data BurstMessage, the message type is `00001001`.

ACK₋₋ SEQ is the acknowledgment sequence number. The base station 108shall set this field to the MSG₋₋ SEQ field from the most recentlyreceived Access Channel 106 message requiring an acknowledgment from theremote metering unit 102 addressed by this message.

MSG₋₋ SEQ is the message sequence number.

ACK₋₋ REQ is the acknowledgment required indicator. The base station 108shall set this field to `1` if the remote metering unit 102 is requiredto acknowledge this message. Otherwise, the base station 108 shall setthis field to `0`.

VALID₋₋ ACK is the valid acknowledgment indicator. To acknowledge themost recently received access channel 106 message from remote meteringunit 102, the base station 108 shall set this field to `1`. Otherwisethe remote metering unit shall set this field to `0`.

ADDR₋₋ TYPE is the address type, which is set in accordance with thetype of identifier being used (i.e. ESN, IMSI, TMSI, etc.).

ADDR₋₋ LEN is the address length. The base station 108 shall set thisfield to the number of octets included in the ADDRESS field.

ADDRESS is the personal station or broadcast address.

MSG₋₋ NUMBER is the message number within the data burst stream. Thebase station 108 shall set this field to the number of this messagewithin the data burst stream.

BURST₋₋ TYPE is the data burst type, and is set according to the valueshown in TSB-58, entitled "Administration of Parameter Value Assignmentsfor TIA/EIA Wideband Spread Spectrum Standards" for the type of thisdata burst.

NUM₋₋ MSGS is the number of messages in this data burst stream.

NUM₋₋ FIELDS is the number of characters in this message.

CHARi is a character. The base station 108 shall include NUM₋₋ FIELDSoccurrences of this field. The base station 108 shall set these fieldsto the corresponding octet of the data burst stream.

Thus, the present invention uses low-cost remote communication devicesoperating on existing wireless communication systems in order to providereal-time reading and control of remote telemetry devices, whileproviding advanced consumer services to customers. By providing wirelessand automatic metering services, the utility company may decrease costsby avoiding labor-intensive sight-reading of meters. Also, the utilitycompany may use real-time data to monitor and adjust the load inresponse to surges and dips in demand. Furthermore, by providing a"gateway" for advanced consumer services, the utility company may alsotake advantage of home-integration technology to perform active loadmanagement, and even interactive informational services.

The previous description of the preferred embodiments is provided toenable any person skilled in the art to make or use the presentinvention. The various modifications to these embodiments will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other embodiments without the use ofthe inventive faculty. Thus, the present invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

We claim:
 1. A wireless remote telemetry system comprising:a first basestation having a code-division multiple access (CDMA) random accesschannel and a CDMA paging channel, said CDMA random access channel forcarrying a plurality of reporting messages and said CDMA paging channelfor carrying a plurality of control messages; a first remote telemetrydevice of a plurality of remote telemetry devices, said first remotetelemetry device for measuring a local parameter, and for transmitting afirst of said plurality of reporting messages over said CDMA randomaccess channel in response to said measurement, and for receiving afirst of said plurality of control messages over said CDMA pagingchannel; and a central controller for receiving said first reportingmessage and for generating said plurality of control messages.
 2. Thesystem of claim 1 further comprising a remote communication unit forrelaying said first control message to said first remote telemetrydevice and for relaying said first reporting message to said basestation.
 3. The system of claim 2 wherein said remote communication unitis a wireless subscriber station.
 4. The system of claim 2 wherein saidremote communication unit is a second CDMA base station.
 5. The systemof claim 2 wherein said remote communication unit is a wireless CDMArepeater.
 6. The system of claim 3 further comprising a user terminalfor displaying user information in response to said measurement of saidlocal parameter and said first control message.
 7. The system of claim 4further comprising a user terminal for displaying user information inresponse to said measurement of said local parameter and said firstcontrol message.
 8. The system of claim 6 further comprising a remoteappliance, said remote appliance being adjusted in response to saidfirst control message.
 9. The system of claim 7 further comprising aremote appliance, said remote appliance being adjusted in response tosaid first control message.
 10. A method of remote telemetering in acode-division multiple access (CDMA) communication system in which afirst base station having a CDMA random access channel and a CDMA pagingchannel communicates with a remote telemetry device and a centralcontroller, said CDMA random access channel for carrying a plurality ofreporting messages and said CDMA paging channel for carrying a pluralityof control messages, said method comprising the steps of:measuring, atsaid remote telemetry device, a local parameter; transmitting, from saidremote telemetry device, a first of said plurality of reporting messagesover said CDMA random access channel in response to said measurement;receiving, in said central controller, said first reporting message;generating, in said local controller, a first of said plurality ofcontrol messages; transmitting said first control message over said CDMApaging channel; and receiving, in said remote telemetry device, saidfirst control message.
 11. The method of claim 10 further comprising thestep of relaying said first control message to said remote telemetrydevice and for relaying said first reporting message to said basestation.
 12. The method of claim 11 further comprising the step ofdisplaying, at a user terminal, user information in response to saidmeasurement of said local parameter and said first control message. 13.The method of claim 12 further comprising the step of adjusting a remoteappliance in response to said first control message.
 14. A remotemetering unit in a code-division multiple access (CDMA) communicationsystem having at least one base station, said at least one base stationhaving a CDMA random access channel and a CDMA paging channel, said CDMArandom access channel for carrying a plurality of reporting messages andsaid CDMA paging channel for carrying a plurality of control messagessaid remote metering unit comprising:a reading interface for generatinga measurement signal in response to reading a measurement device; amicroprocessor for generating a first of said plurality of reportingmessages in response to said measurement signal; and a CDMA transmitterfor transmitting said first reporting message over said CDMA randomaccess channel.
 15. The remote metering unit of claim 14 furthercomprising:a tampering sensor for generating a tampering signal; and amultiplexer for multiplexing said tampering signal with said measurementsignal, said microprocessor further for generating a second of saidplurality of reporting messages in response to said tampering signal,and said CDMA transmitter further for transmitting said second reportingmessage over said CDMA random access channel.
 16. The remote meteringunit of claim 15 wherein said remote metering unit is coupled to atleast one electrical power line, said remote metering unit furthercomprising at least one step down transformer for generating avoltage-level signal in response to a voltage level of said at least oneelectrical power line, said multiplexer further for multiplexing saidvoltage-level signal with said tampering signal and said measurementsignal, said microprocessor further for generating a third of saidplurality of reporting messages in response to said voltage-levelsignal, and said CDMA transmitter further for transmitting said thirdreporting message over said CDMA random access channel.
 17. The remotemetering unit of claim 14 further comprising:a CDMA receiver forreceiving a control message over said CDMA paging channel; a power-linecarrier interface for translating said received control message into apower-line carrier control signal; and at least one power-linetransceiver for transmitting said power-line carrier control signal oversaid at least one electrical power line.
 18. The remote metering unit ofclaim 14 further comprising:an antenna; a CDMA receiver for receiving afirst of said plurality of control messages over said CDMA pagingchannel; a switch for alternately coupling said CDMA transmitter or saidCDMA receiver to said antenna.
 19. The remote metering unit of claim 18wherein said CDMA paging channel operates in a slotted mode, and whereinsaid switch couples said CDMA transmitter to said antenna only duringtimes not associated with an assigned paging slot of said remotemetering unit.